This invention relates to a pellicle mounting apparatus.
A reticle plate, usually made of glass or quartz, can be used as a mask as part of the process of producing various semiconductor devices such as integrated circuits. If any dust or particles fall onto the surface of the mask, this will produce an inaccurate reproduction from the mask including spots representing the dust or particles. To protect the mask from dust or other particles, a pellicle (which consists of a thin transparent membrane) is positioned adjacent to and spaced from the mask so that any dust or other particles will fall onto the membrane rather than the mask. Thus, the dust and other particles will be out of focus when the mask is used.
Pellicles are generally formed with a frame member supporting the periphery of the membrane. The frame member is attached to the reticle by an adhesive so that the membrane is maintained in a fixed relationship with the mask. The frame member itself is extremely fragile and susceptible to damage or distortion by any direct pressure or flexing of the pellicle.
A pellicle frame tray, such as a MicroLithography Inc. Pellicle Tray (Part Number xe2x80x9cCAN34P0061xe2x80x9d), is often used in assembling a reticle to a framed pellicle. The use of the tray provides some additional reinforcement of the pellicle frame member during assembly.
In general, in one aspect, the invention features an apparatus for mounting a pellicle to a reticle. The apparatus includes: a base; a first holder coupled to the base and including two edges positioned to support a first object below its center of gravity and secure the first object in substantially vertical alignment with the base, the first object including one of the pellicle and the reticle; a second holder slidably coupled to the base and including two edges positioned to support a second object below its center of gravity and secure the second object in substantially vertical alignment with the base, the second object including the other of the pellicle and the reticle; and a pressure applicator assembly slidably coupled to the base to adjustably apply pressure to a periphery of the second object held in the second holder and drive it against a corresponding periphery of the first object held in the first holder.
In some embodiments, the apparatus further includes a bi-directional actuator coupled to the pressure applicator assembly to drive and retract the pressure applicator assembly in relation to the base. For example, during operation the actuator can drive the pressure applicator assembly against the second object to cause the second holder to slide towards the first holder.
In general, in another aspect, the invention features an automated apparatus for mounting a pellicle to a reticle. The apparatus includes: a base; a first holder coupled to the base and positioned to support a first object in substantially vertical alignment to the base, the first object including one of the pellicle and the reticle, the first holder including at least one sensor for determining the presence or absence of the first object in the first holder; a second holder slidably coupled to the base and positioned to support a second object in substantially vertical alignment with the base, the second object including the other of the pellicle and the reticle, the second holder including at least one sensor for determining the presence or absence of the second object in the second holder; a pressure applicator assembly slidably coupled to the base to adjustably apply pressure to a periphery of the second object held in the second holder and drive it against a corresponding periphery of the first object held in the first holder; and an actuator coupled to the pressure applicator assembly and responsive to the sensors in the first and second holder to drive the pressure applicator assembly towards the first holder for a time interval when the first and second object are in the first and second holders.
For example, the sensors can include retroflective light sensors or mechanical sensors. In some embodiments, a user sets the time interval. Alternatively, a controller coupled to the actuator can set the time interval in an automated fashion. Furthermore, during operation the actuator can retract the pressure applicator assembly away from the first holder after the time interval.
In general, in another aspect, the invention features an apparatus for mounting a pellicle to a reticle. The apparatus includes: a base; a first holder coupled to the base and positioned to support a first object in substantially vertical alignment to the base, the first object including one of the pellicle and the reticle; a second holder slidably coupled to the base and positioned to support a second object in substantially vertical alignment with the base, the second object including the other of the pellicle and the reticle; and a pressure applicator assembly slidably coupled to the base to adjustably apply pressure to a periphery of the second object held in the second holder and drive it against a corresponding periphery of the first object in the first holder. The pressure applicator assembly includes: a slidable bracket coupled to the base; a back plate rigidly attached to the slidable bracket; an intermediate plate pivotally coupled to the back plate along at least one axis; and a front plate pivotally coupled to the intermediate plate along at least one other axis, the front plate having a plurality of contact points configured to align with the periphery of the second object held in the second holder.
In some embodiments, the pressure applicator assembly further includes a first at least one tensioning device positioned to apply tension to the pivotal coupling between the back plate and the intermediate plate, and a second at least one tensioning device positioned to apply tension to the pivotal coupling between the front plate and the intermediate plate. For example, the first and second tensioning devices can include a plurality of springs.
In general, in another aspect, the invention features an apparatus for mounting a pellicle to a reticle. The apparatus includes: a base; a first holder coupled to the base and positioned to support a first object in substantially vertical alignment to the base, the first object including one of the pellicle and the reticle; a second holder slidably coupled to the base and positioned to support a second object in substantially vertical alignment with the base, the second object including the other of the pellicle and the reticle; a pressure applicator assembly slidably coupled to the base to adjustably apply pressure to a periphery of the second object held in the second holder and drive it against a corresponding periphery of the first object held in the first holder; and a laminar air flow source configured to provide air flow along the substantially vertically aligned first and second objects.
Embodiments of any of the different aspects of the invention described above can include any of the following features.
The pressure applicator assembly can be configured to adjust to the orientation of the periphery of the second object and apply uniform pressure to the periphery of the second object.
The first object can include a pellicle tray supporting the pellicle. Alternatively, the first object can be the pellicle, e.g., a framed pellicle. Furthermore, the pellicle can include an adhesive along the periphery of one of its faces.
The first holder can be rigidly coupled to the base and include a backing plate positioned to support a back periphery of the first object. Moreover, the first holder can further include: an upright bracket coupled to the base; and a translation frame rigidly coupled to the upright bracket and to the backing plate, the translation frame configured to allow adjustment of the backing plate in a substantially vertical plane relative to the base. Alternatively, the first holder can be slidably coupled to the base, and the apparatus can further includes a backing plate rigidly secured to the base and extending substantially vertically from the base, wherein the backing plate is configured to support a back periphery of the first object.
The actuator can be a bi-directional cylinder, e.g., a pneumatic cylinder, configured to drive the pressure applicator assembly towards the first holder and alternately to retract the pressure applicator assembly away from the first holder.
The apparatus can further include a shock absorber coupled to at least one of the pressure applicator and the second holder and positioned between the pressure applicator and the second holder. Moreover, the apparatus can further include a shock absorber coupled to at least one of the first holder and the second holder and positioned between the first holder and the second holder.
Embodiments of the invention may include many advantages.
For example, the apparatus can allow mounting of a framed pellicle to a reticle with minimal distortion or damage to the individual or completely assembled parts. The reticle holder and pellicle tray holder both utilize support edges that provide support below their center of gravity, thus the reticle and pellicle are supported vertically without mechanical or pneumatic pressure. Furthermore, the pressure applicator can uniformly apply pressure to the periphery of the reticle and pellicle during assembly. Moreover, the apparatus can also provide for integrated laminar airflow to remove contaminants during mounting and assembly.
Furthermore, embodiments of the apparatus can be automated to provide highly accurate alignment of the framed pellicle to the reticle over repeated mountings. Also, the use of a pellicle tray can accommodate the use of different sized pellicle frames.
Other features, objects, and advantages of an embodiment will be apparent from the following description and drawings, and from the claims.